1. Field of the Invention
The present invention relates to an image forming apparatus such as a copying machine, a printer and the like, and more particularly, it relates to a fixing apparatus for pinching and conveying a recording material.
2. Related Background Art
In conventional image forming apparatuses of this kind such as laser beam printers, copying machines and the like, generally, a toner image born on an image bearing member such as a photosensitive drum is transferred onto a recording material such as a paper by a transferring process and is fixed to the recording material as a permanent image by a fixing process.
In this fixing process, a heating device for fixing the toner image to the recording material by heat and fusion is used, in which the recording material is pinched and conveyed by a heating roller a temperature of which is maintained to a predetermined value, and a pressing roller having an elastic layer and urged against the heating roller, so that the non-fixed toner image is fixed to the recording material.
On the other hand, recently, in plate of such a fixing process, film fixing apparatuses capable of increasing a temperature for a short time from power-ON, such as fixing apparatuses as disclosed in Japanese Patent Application Laid-Open Nos. 63-313182 and 2-157878 have been proposed.
An example of a fixing apparatus as a background art of the present invention is shown in FIG. 4. In this fixing apparatus, by heating and pressurizing a recording material by a fixed heating body 202, a heat-resistive film 201 (referred to as xe2x80x9cfixing filmxe2x80x9d hereinafter) conveyed while being opposed to and urged against the heating body 202, and a pressing roller 205 urged against the heating body 202 via the fixing film 201, a non-fixed toner image on the recording material is fixed to the recording material.
However, a small amount of non-fixed toner is not fixed to the recording material but is adhered to the fixing film 201. The toner adhered to the film 201 is transferred from the film 201 to a surface of the pressing roller 205.
Since the surface of the pressing roller 205 is covered by fluororesin (fluorine resin) so that the toner is hard to be adhered thereto, the toner adhered to the surface of the pressing roller 205 is adhered to a back surface of a next recording material while the recording material is being passed through a fixing nip portion. Accordingly, the toner was not almost accumulated on the surface of the pressing roller 205.
By the way, in recent years, neutral papers have been used as recording material for the purpose of long term storage, with the result that usage of papers including calcium carbonate as a filler have been increased.
It is known that toner is hard to be adhered to calcium carbonate, and, thus, when the papers including calcium carbonate are passed though the fixing apparatus as the recording materials, since the toner on the pressing roller 205 is hard to be adhered to the recording material, the toner is gradually accumulated on the surface of the pressing roller 205. In this condition, when the fixing apparatus continues to be used, the toner is stuck to the surface of the pressing roller 205 to contaminate the latter.
Further, usage of papers including talc as main material has also been increased. Such a paper is apt to generate paper powder. Even when a large amount of paper powder exists on the surface of the paper, there is the tendency for making adhesion of toner difficult. Accordingly, when the talc papers continue to be used, the toner adhered to the pressing roller becomes hard to be returned to the recording material, with the result that the toner is accumulated on and stuck to the surface of the pressing roller 205.
Particularly, in the transferring process utilizing a transfer roller, while a peripheral speed of the transfer roller is set to be greater than a conveying speed of the paper to enhance transferring efficiency, by doing so, the paper powder is apt to be generated on the back surface of the recording material, with the result that, since the toner on the pressing roller 205 is hard to be adhered to the back surface of the recording material, the toner will be further accumulated on the surface of the pressing roller 205.
To avoid this, as shown in FIG. 4, it is considered that a cleaning member 220 is contacted with the surface of the pressing roller 205 to remove the toner.
However, in such a case, if a certain number of recording materials are passed, the contamination will be accumulated on the cleaning member 220, an such contamination passes through the cleaning member 220 to be adhered to the recording material. Thus, when the contamination is accumulated to some extent, the cleaning member must be exchanged periodically.
Further, if the exchange is forgotten, the cleaning efficiency will be insufficient. Consequently, the toner is stuck to the surface of the pressing roller 205 and the paper is adhered to such toner, with the result that paper jam on the pressing roller occurs, and, in some cases, it becomes difficult to remove the recording material from the pressing roller 205, thereby requiring repair.
Further, there is a problem that the surface of the pressing roller 205 is damaged by sliding contact between the cleaning member 220 and the pressing roller.
An object of the present invention is to provide an image forming apparatus in which a surface of a driving roller is cleaned by a recording material efficiently.
Another object of the present invention is to provide an image forming apparatus comprising an image bearing member for bearing an image, a transferring member for forming a transfer nip portion between the image bearing member and the transferring member, a rotary member contacted with an image on a recording material, and a driving roller for forming a fixing nip portion between the rotary member and the driving roller and for driving the rotary member, wherein the recording material is pinched and conveyed and the image on the image bearing member is transferred onto the recording material in the transfer nip portion, and wherein the recording material bearing the image thereon is pinched and conveyed and the image is fixed to the recording material in the fixing nip portion, and, when the image is transferred in the transfer nip portion, the image is fixed to at least a recording material having maximum size in the fixing nip portion, and a peripheral speed of the driving roller is always greater than a conveying speed of the recording material in the transfer nip portion.
The other object of the present invention is to provide a cartridge and image forming apparatus, in which information regarding execution of the correction sequence is stored in the cartridge.